The present patent application claims the benefit of earlier Japanese Patent Application No. 2000-76112 filed Mar. 17, 2000, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to an air damper, and more specifically, to an improved structure of a cylindrical air damper installed in, for example, the glove box of an automobile.
2. Description of the Related Art
A conventional cylindrical air damper fixed to the glove box of an automobile is disclosed in, for example, Japanese Utility model Registration No. 2557064. This type of air damper is used to dampen the abrupt opening motion of the glove box, or to prevent unpleasant noise due to sudden opening. The air damper allows the glove box to open slowly by pivoting about the pivoting axis against the gravitational force.
The conventional air damper comprises a cylinder with openings at both ends, and a piston moving in the cylinder. A string is coupled with the piston, and it extends out of the cylinder from the remote end. A valve is attached to the base or the close end to control the quantity of the air passing through the cylinder. A guide cap is attached to the remote end of the cylinder to guide the string. A compression coil spring is inserted between the guide cap and the piston.
The air damper is fixed to, for example, the instrument panel, which is the back wall of the glove box. The string extending from the guide cap of the cylinder is coupled to the glove box. When the glove box is unlocked to start opening, the string is pulled out of the cylinder, and the piston coupled to the spring moves inside the cylinder, while compressing the coil spring. Consequently, the air flows into the cylinder via the valve, which gives the damper effect to the cylinder. With this arrangement, the glove box slowly opens toward the opening position.
When the glove box is pushed toward the closed position, the piston is pushed back towards the valve by the restoring force of the compression coil spring, pulling the string back inside the cylinder. At this time, the valve is open to let the air stored in the cylinder to escape, and accordingly, the piston moves back to the home position smoothly.
The full open position of the glove box using an air damper has to be regulated. In general, a guide groove is formed in the instrument panel itself or the cover sheet furnished to an appropriate place on the instrument panel, as disclosed in Japanese Utility Model No. 2587728. A stopper pin is provided to the side face of the glove box in such a manner that the stopper pin moves along the guide groove as the glove box is opened or closed. If the glove box slowly opens by its own weight, the stopper pin moves in the groove, and comes to the end of the groove. The abutment between the stopper pin and the end of the groove regulates the full open position of the glove box.
However, providing a separate component for regulating the full open position of the glove box causes the entire structure of the glove box to become complicated, while limiting the storage capacity of the box. It may be proposed that the air damper itself be used to regulate the full open position of the glove box, making use of the maximum compressed position of the spring. Using the air damper as the open position regulation means, however, causes other problems. The compression coil spring is weakened due to excessive load of the glove box, brittle portions of the air damper may be broken, and the full open position fluctuates because of the spring force. These problems have prevented the air damper from being used as the open position regulation means as it is.
Therefore, the invention was conceived to overcome these problems in the prior art technique. The major objective of the invention is to provide an improved structure of an air damper used in the glove box of an automobile. The improved air damper is capable of functioning as a means for regulating the full open position of the glove box, without causing the compression coil spring of the air damper to be damaged or deteriorated.
To achieve the objective, an air damper according to the invention comprises a cylinder with a first open end and a second end, a guide cap covering the first open end, and a piston moveable in the cylinder. A compression coil spring is inserted in the cylinder between the piston and the guide cap. The coil spring forces the piston toward the second end of the cylinder in the free state. A string is coupled with the piston, and it extends out of the cylinder. As a feature of the invention, a stopper means is positioned between the guide cap and the piston n order to stop the piston before the compression coil spring is fully compressed when the string is pulled to cause the piston to move toward the guide cap.
The stopper means is located inside the compression coil spring. This arrangement allows the air damper to be kept compact, without requiring an extra space for accommodating the coil spring.
The stopper means is connected to the guide cap, or alternatively, the stopper means is connected to the piston.
Preferably, the piston has a hook piece facing the guide cap. The hook piece is threaded with the string in such a manner that at least one end of the string is taken out of the cylinder via the guide cap. In other words, the string is doubled at the hook piece, and moveable through the hook piece. The one end of the string is coupled with the side edge of the glove box. When the glove box is opened, the string is pulled out of the cylinder, which causes the piston to move toward the guide cap. Since there is a stopper means between the piston and the guide cap, the piston strikes the stopper means before the compression coil spring is fully compressed. This arrangement can prevent the coil spring from being deteriorated due to excessive load by the weight of the glove box. Simultaneously, the stopper means reliably defines the full open position of the glove box, because the glove box is retained in a stable manner at a position determined by the length of the stopper means.